Capillary adaptor



Jan. 8, 1957 E. H. MAGESTER 2,776,550

CAPILLARY ADAPTOR Filed Oct. 21, 1952llllllIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII I I'll Iltl'llrllllllll,

I'll(IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII! 1 Inventor: Earl H. Magester;

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United States Patent CAPILLARY ADAPTOR Earl H..Magester, Erie, Pa.,assignor to General Electric Company, a corporation of New YorkApplication October 21, 1952,,Serial No. 316,023

2 Claims. (Cl. @62126) My invention relates to refrigerating systems andmore particularly to capillary adaptors for-use in such systems.

In many present day refrigerating systems a restricting, or capillary,tube is employed between the coudenser and the evaporator thereof formetering flow of refrigerant and for maintaining the desiredpressuredifference between the condenser and'the evaporator. Thiscapillary tube consists of a substantial length of tubing of relativelysmall diameter so as to effect the necessary pressure drop. O11 theother hand, the tubing of the evaporator to which the capillary tube isconnected is of a substantially greater diameter since it is necessaryto provide for relatively easy flow of refrigerant through theevaporator, and particularly it is necessary that the diameter be ofsufficient size that blocking of flow is not effected as a result ofvaporization of refrigerant in the evaporator. It is customary toprovide an adaptor for connecting the relatively small capillary tube tothe larger tubing of the evaporator. In accordance with my invention,the adaptor is arranged so that a predetermined length of capillaryprojects beyond the end thereof and so that the adaptor itself serves tolimit the proved assembly including an adaptor for connecting .a

capillary tube to tubing of larger diameter.

It is another object of my invention to provide an improvedarrangement-for minimizing noise in refrigerating systems.

It is a further object of my invention to provide an ii adaptor assemblywhich limits the strain on the joint between the capillary tube and theadaptor.

It is still another object of my invention to provide an improved methodfor assembling an adaptor to conmeet a capillary tube and evaporatortubing of larger diameter.

Further objects and advantages of my invention will become apparent asthe following description proceeds and the features of novelty whichcharacterize my invention will be pointed outwith particularity in theclaims annexed to and forming a part of this specification.

In carrying out the objects of my invention, the capillary tube isassembled to extend through the length of the adaptor and apredetermined distance beyond the small end thereof, and the capillarytube is brazed to the adaptor at this small end. This assembly of thecapillary tube and the adaptor is then inserted Within the end of theevaporator tube with the small end of the adaptor and the projecting endof the capillary tube extending into the evaporator tubing. The assemblyis completed by brazing the large end of the adaptor to the evaporatortubing.

For a better understanding of my invention, reference may be had to theaccompanying drawing in which ICC Fig. 1 is a schematic diagram of arefrigerating system incorporating an embodiment of my invention.

Fig. 2 is an enlarged sectional view of a portion of the'refrigeratingsystem of Fig. 1 showing the adaptor arrangement.

Referring to Fig. 1, there is shown a hermetically-sealed refrigeratingsystem which includes a refrigerating unit 1 from which compressedrefrigerant is discharged to a condenser 2. Liquefied refrigerant isdischarged from the condenser 2 and supplied to the evaporator 3 througha restricting, or capillary, tube 4. Vaporized refrigerant collects in aheader 5-of the evaporator and is returned to the refrigerating unit 1through a section line 6.

'A capillary tube is used in manypresent day refrigerating systems formetering liquid refrigerant from the condenser to the evaporator and formaintainingthe necessary pressure drop between the condenser and theevaporator. To accomplish these results, the capillary tube 4 is ofsubstantial length and is necessarily of relatively small diameter. Onther other hand, the evaporator 3, which may be of the type widely usedat present, is made from tubing or conduit which is of a substantiallylarger diameter than the capillary tube 4. This is necessary in orderthat ready flow of refrigerant through the passes of evaporator 3 bepermitted and in order that vaporization of refrigerant in theevaporator not cause any substantial blocking of flow therethrough. Anadaptor 7 is provided for connecting the small capillary tube in sealedrelationship with the much larger tubing of the evaporator 3. i

The specific construction shown is illustrated in Fig. 2. As thereshown, the adaptor comprises an elongated tapering tube of substantiallength. The capillary tube 4 extends entirely through the length of theadaptor 7 and the end 8 of the capillary tube projects a predetermineddistance beyond the small end 9 of the tapering adaptor 7. The capillarytube 4 is brazed or otherwise secured to the small end9 of the adaptor,as indicated at 10, to form a sealed joint at this point. The largediameter end of the adaptor 7 is brazed or otherwise secured, asindicated at 11, to the end of the tubing or conduit of the evaporator 3to provide a sealed joint at this point. The end of the adaptor mayextend beyond the end of the tubing of the evaporator 3, as shown inFig. 2, and includes a flared mouth 12.

Brazing of the capillary tube at 10 removes some of the temper from thetube and somewhat weakens the tube. It will be realized thatrefrigerating systems of the type disclosed receive a substantial amountof handling during assembly thereof within refrigerator cabinets,freezers, or the like, and there is necessarily, with the length oftubing involved, a bending force applied to the tubing. Repeated bendingof the capillary tube during such assembly of the refrigerating system,particularly bending through a substantial are as is possible withconventional assemblies, may in some cases cause a breaking of thecapillary tube in the region of the brazed area 10. By the arrangementhere disclosed, however, the capillary tube in the region extending fromthis brazed area 10 is enclosed within the surrounding adaptor 7 for asubstantial distance and the maximum bending of the capillary tube,insofar as this bending is applied at the joint 10, is limited byengagement of the capillary tube with the mouth 12 of the adaptor.

In conventional systems, it has been customary to seal the large end ofthe adaptor to the end of the evaporator tubing with the small end ofthe adaptor projecting beyond the end of the evaporator tubing. It hasthen been customary to merely insert the end of the capillary tube intothe small end of the adaptor, brazing the capillary tube 'to this smallend. It can be seen that this type of construction provides no limit forthe bending of the capillary tube during the subsequent operations ofassembling the system in an appropriate cabinet and this bending force,in large measure, is applied to the weakened area in the region of thebrazed joint between the capillary tube and the adaptor. A tendencytoward breakage of the capillary tube in the weakened brazed area andthe resultant breaking of the seal of the hermetic system is minimizedby the strain-limiting adaptor arrangement of my invention.

In the conventional arrangement described above, moreover, it isimpossible to tell with any degree of accuracy the extent to which thefree end of the capillary tube projects into the adaptor from the smallend thereof. Since this free end of the capillary tube has a tendency tovibrate, acting somewhat as a reed at low natural frequency an undulygreat length projecting into the adaptor gives rise to an undesirablyhigh noise level. By the adaptor arrangement of my invention, thecapillary tube extends entirely through the adaptor, and the free end ofthe capillary tube extends beyond the small end of the adaptor. Theexact length of capillary tube so projecting is, therefore, clearlyvisible at the time the brazed joint is made. The capillary tube cantherefore easily be made to project any desired predetermined distancebeyond the end of the adaptor.

In making the assembly shown in Fig. 2, the capillary tube is firstinserted from the large end of the adaptor 7 in a manner to extendentirely through the adaptor with the end 8 of the capillary tubeprojecting or extending slightly beyond the small end 9 of the adaptor.At this point in the manufacture of the assembly, the length ofcapillary tube so projecting can be clearly determined by easyinspection and this length is set to the desired amount previouslydetermined. The end 9 of the adaptor is then brazed, as indicated at 10,to the capillary tube 4 to form a sealed joint. After this operation hasbeen completed, the assembly including the capillary tube and theadaptor is inserted in the end of the tubing of the evaporator 3 withthe projecting end 8 of the capillary tube and the small end 9 of theadaptor 7 projecting into the tubing of the evaporator. The large end ofthe adaptor 7 is then brazed, as indicated at 11, to the evaporatortubing to form a sealed joint at that point. I t can be seen that thelength of capillary tube projecting beyond the small end 9 of theadaptor can be set exactly since it is clearly visible for inspection atthe time this portion of the assembly is being made. It can be seenfurther that with the construction employed which includes an adaptor ofsubstantial length and with a capillary tube extending through the fulllength of this adaptor, the bending of the capillary tube and the strainimported to the brazed joint 10 thereby is limited by engagement of thecapillary tube with the large end or mouth 12 of the adaptor 7.

While I have shown and described a specific embodiment of my invention,I do not desire my invention to be limited to the particularconstruction shown and described and I intend by the appended claims tocover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In a refrigerating system, a capillary tube, an evaporator includingcontinuous tubing of larger diameter than said capillary tube, anadaptor for connecting said capillary tube and said evaporator tubing,said adaptor comprising an elongated tapering tube, 'said capillary tubeextending through said adaptor and projecting a predetermined distancebeyond the small end of said adaptor, said small end of said adaptorbeing brazed to said capillary tube said adaptor being assembled in saidevaporator tubing with the small end of said adaptor and the projectingend of said capillary tube extending into said evaporator tubing, thelarger end of saidadaptor being brazed to the end of said evaporatortubing adjacent the point of maximum taper diameter, said larger end ofsaid adaptor extending a substantial distance beyond the end of saidevaporator tubing to limit the bending movement of said capillary tube.

2. ln a refrigerating system, a capillary tube, an evaporator includingcontinuous tubing of larger diameter than said capillary tube, anadaptor for connecting said capillary tube and said evaporator tubing,said adaptor comprising a tapering tube of said substantial length, saidcapillary tube extending through said adaptor and projecting apredetermined distance beyond the small end of said adaptor, said smallend of said adaptor being brazed to said capillary tube, said adaptorbeing assembled in said evaporator tubing with the small end of saidadaptor and the projecting end of said capillary tube extending intosaid evaporator tubing, the larger end of said adaptor being brazed tothe end of said evaporator tubing adjacent the point of maximum taperdiameter, said larger end of. said adaptor extending a substantialdistance beyond the end of said evaporator tubing and terminating in aflared mouth, said capillary tube engaging said flared mouth after apredetermined bending movement of said capillary tube for limiting saidbending movement and for limiting strain on the brazed portion of saidcapillary tube.

References Cited in the tile of this patent UNITED STATES PATENTS2,073,863 ,Bird Mar. 16, 1937 2,200,694 Gerecke May 14, 1940 2,611,238Fryer Sept. 23, 1952

